A variety of methods are utilized to produce a post hole, involving both mechanized and non-mechanized means. Mechanized post hole diggers generally comprise a rotating auger having helical flighting and a cutting head to aid in loosening the soil to be excavated. As the auger rotates, the loosened soil is conveyed out of the hole by the screw-like movement action of the helical flighting formed into the auger. While the helical flighted type of auger effectively produces a hole, it leaves loose soil at the bottom of the hole and spatters the soil at the top of the hole surrounding it. It is typical for some of the excavated soil deposited around the top of the hole by the auger fighting to fall back into the hole during post installation. This requires a further step in removing the loose soil from the bottom of the post hole before a post is planted into the newly dug post hole.
An installed post should be stabilized to withstand and support a load, so it is desirable to compact the earth walls forming the post hole so that the post can be solidly planted to limit future settling of the post. In order to achieve a properly compacted hole, the loose soil must either be first removed by hand or compacted directly in place. Additionally, when setting posts in concrete, the soil that is excavated from the hole is replaced by concrete which requires the overburden soil to be removed after the post is set. Ensuring the soil is properly compacted and removing the excavated overburden soil can be very time consuming and labor intensive.
Although the auger's helical flighting effectively scrapes away earth to form the excavated post hole, the cutting action disturbs the stability of the hole wall and leaves the remaining wall subject to crumbling and degradation. Occasionally, it is advantageous to enhance the stability of the hole's wall by compacting the wall's surface. This action requires a further step after the use and retraction of the helical flighted auger, and the removal of the loose soil from the hole.